A considerable amount of effort has been expended in recent years to develop and the technology of flame retardancy, particularly as it relates to the plastics field. A variety of compounds or combination of compounds have been found which, when incorporated in synthetic polymers, impart good flame retardant characteristics thereto through various mechanisms such as an interference with the flame reaction, by the exclusion of air or by insulating the substrate from heat, preventing further decomposition to produce additional fuel for further combustion. Of the various flame retardant agents developed, those containing antimony, halogen or phosphorus are perhaps the most widely used. While flame retardant agents comprising combinations of antimony-containing compounds and halogen-containing compounds have been found to be effective when incorporated in various plastic compositions, antimony itself is toxic and the recent rise in the cost of this material, which is available only from foreign sources, has occasioned problems not only from an economic standpoint, but also from the standpoint of the availability of the material.
The present invention overcomes many of the problems and disadvantages associated with other flame retardant compositions when incorporated in styrenic resin systems, particularly ABS resins, by providing a flame retardant agent which is more economical than antimony-containing flame retardant agents on a cost-effectiveness basis, is of comparatively low toxicity in comparison to antimony-containing agents, is available from domestic sources in good quantities and which, by careful selection of compounds and concentrations, imparts flame retardancy characteristics to styrenic plastics sufficient to pass even the most severe and stringent flammability tests.